The present invention relates to a method and apparatus for measuring sperm motility, i.e., the spontaneous movement of sperm cells.
Sperm motility is considered to be one of the most important criteria influencing the fertility of sperm cells and is commercially important in determining suitability of a specimen for the artificial insemination of animals, for example. A large number of techniques have been devised or proposed for measuring sperm motility, as described for example in the following publications: L. Nelson, "Spermatozoan Motility," Endocrinology Male Reproductive System, Section 7, Volume 5, 1975; D. F. Katz and H. M. Dott, "Methods Of Measuring Swimming Speed Of Spermatozoa," J. Reprod.Fert. 45,263-272 (1975); K. A. Wall and M. A. Boone, "Objective Measurement Of Sperm Motility," Poultry Science 52:657-660 (1973); and R. Rikmenspoel, "Electronic Analyzer For Measuring Velocities & The Concentration Of Spermatozoa," The Review Of Scientific Instruments, Volume 35, No. 1, January 1964. The known techniques, however, are generally considered not entirely satisfactory for a number of reasons, mainly because they usually require dilution of the specimen being tested, and often produce inadequate, inaccurate, and/or conflicting results.
Thus, one known approach is based on the continuous examination of the movement of individual sperm cells, this being done usually by visual or photographic observation. One of the most serious drawbacks of this approach is that it requires dilution of the specimen to enable distinguishing individual sperm cells, and then extrapolation to "in vivo" condition. The results obtained are therefore not always accurate since the precise mechanism of the dilution effect is not always known. In addition, photographic procedures introduce a substantial delay between the time the measurements are taken and the time the results are available, during which time further changes may have already occurred in the specimen.
Another known approach for measuring sperm motility is based on examining the specimen at several discrete time intervals, e.g., by multiple photographic exposures, to determine the gross property of the entire suspension at these discrete intervals, this information then being translated, by probability statistical considerations, to an indication of sperm motility by determining the fluctuations in the gross property at these discrete intervals. This approach, however, also usually requires dilution of the suspension to enable discerning individual sperm cells. In addition, it also introduces a substantial delay before the results are available. Further, the processing of the information usually requires complicated and expensive equipment, such as a computer.